1. Field of the Invention
The invention relates to an encapsulated measuring apparatus usable in several mounting positions, including a measuring scale and a scanning assembly, both of which are placed in a prismatic hollow body for protection against environmental influences. The prismatic hollow body is provided with an aperture which is continuous in a direction of measurement and is sealed by means of sealing members. A means for connecting the scanning assembly to another object, such as the carriage of a machine tool, extends through the aperture.
2. Description of the Prior Art
In the prior art measuring apparatus are provided, such as disclosed in Burns U.S. Pat. No. 2,833,303, wherein a slot is mounted in one of the walls of the hollow body and is sealed by means of flexible sealing lips arranged in a roof-like manner. The slot, and in particular the area where the sealing lips meet, are near the center of a wall of the hollow body, and the sealing lips are fastened to remaining projecting bridges or seal retainers of identical length. Encapsulated measuring apparatus with sealing lips applied near the center of the wall of the hollow body are arrangeable only in certain mounting positions, otherwise there would be danger of penetrating liquid such as coolant fluids collecting within the hollow body and possibly causing contaminations at the measuring rod.
West German Offenlegungsschrift No. 2,032,585 discloses an encapsulated measuring apparatus with roof-shaped sealing lips arranged near the edge of the hollow body. More specifically the sealing lips are accommodated inside the hollow body. In that encapsulated measuring apparatus penetrating liquid such as coolant fluids also collects within the hollow body in certain mounting positions, particularly where the connecting means for the scanning unit occupies a horizontal position, so that the penetrating liquid can only flow off from the columns at the sealing lips after reaching a certain level.